1. Field of the Invention
The present invention is directed to a manually operated dispensing pump and more particularly to a finger-operated pump adapted for mounting on a container of liquid to be dispensed.
2. Brief Description of Background Art
Container-mounted, finger-operated dispensing pumps are well known and are used for dispensing liquids having widely varying flow characteristics. The form of discharge from these pumps can vary from a fine spray to a slow moving flow.
Typically, container-mounted dispensing pumps employ fixed and movable pump members forming a variable volume pump chamber and one-way valves controlling the flow into and out of the pump chamber. Various types of one-way valves, including ball check valves and elastomeric valves, are employed in these dispensing pumps.
A dispensing pump disclosed in U.S. Pat. No. 3,406,909 issued to Pfeiffer employs elastomeric one-way valves, known as "duckbill" valves, for controlling flow into and from the pump chamber. These valves operate reliably and are relatively inexpensive. Their one-piece construction simplifies the assembly of a dispensing pump in which they are employed.
Many dispensing pumps incorporate a feature which allows them to be placed in a "shipping" position to prevent leakage through the pump if they are upended. A common pump of this type employs a reciprocable plunger which can be locked in a depressed position to seal the pump against leakage. Applicants are not aware of dispensing pumps employing duckbill pump valves which can be placed in a shipping position to prevent leakage through the pump.